[ovs-dev] [PATCH v2 1/3] conntrack: Do not create new connections from ICMP errors.

[Daniele Di Proietto]

ICMP error packets (e.g. destination unreachable messages) are
considered 'related' to another connection and are treated as part of
that.

However:

* We shouldn't create new entries in the connection table if the
  original connection is not found.  This is consistent with what the
  kernel does.
* We certainly shouldn't call valid_new() on the packet, because
  valid_new() assumes the packet l4 type (might be TCP, UDP or ICMP)
  to be consistent with the conn_key nw_proto type.

Found by inspection.

Fixes: a489b16854b5("conntrack: New userspace connection tracker.")
Signed-off-by: Daniele Di Proietto <diproiettod at vmware.com>
---
v2: Handle ICMP error for non existing connection in else branch without
    restructuring the whole code flow.
---
 lib/conntrack.c         |  6 +++++-
 tests/system-traffic.at | 27 ++++++++++++++++-----------
 2 files changed, 21 insertions(+), 12 deletions(-)

diff --git a/lib/conntrack.c b/lib/conntrack.c
index 7c50a28..9bea3d9 100644
--- a/lib/conntrack.c
+++ b/lib/conntrack.c
@@ -247,7 +247,11 @@ process_one(struct conntrack *ct, struct dp_packet *pkt,
             }
         }
     } else {
-        conn = conn_not_found(ct, pkt, ctx, &state, commit, now);
+        if (ctx->related) {
+            state |= CS_INVALID;
+        } else {
+            conn = conn_not_found(ct, pkt, ctx, &state, commit, now);
+        }
     }
 
     write_ct_md(pkt, state, zone, conn ? conn->mark : 0,
diff --git a/tests/system-traffic.at b/tests/system-traffic.at
index 9ea6d6b..a5023d3 100644
--- a/tests/system-traffic.at
+++ b/tests/system-traffic.at
@@ -1331,12 +1331,8 @@ ADD_VETH(p1, at_ns1, br0, "172.16.0.2/24")
 
 dnl Allow any traffic from ns0->ns1. Only allow nd, return traffic from ns1->ns0.
 AT_DATA([flows.txt], [dnl
-priority=1,action=drop
-priority=10,arp,action=normal
-priority=100,in_port=1,udp,ct_state=-trk,action=ct(commit,table=0)
-priority=100,in_port=1,ip,ct_state=+trk,actions=controller
-priority=100,in_port=2,ip,ct_state=-trk,action=ct(table=0)
-priority=100,in_port=2,ip,ct_state=+trk+rel+rpl,action=controller
+table=0,ip,action=ct(commit,table=1)
+table=1,ip,action=controller
 ])
 
 AT_CHECK([ovs-ofctl --bundle replace-flows br0 flows.txt])
@@ -1345,22 +1341,31 @@ AT_CAPTURE_FILE([ofctl_monitor.log])
 AT_CHECK([ovs-ofctl monitor br0 65534 invalid_ttl --detach --no-chdir --pidfile 2> ofctl_monitor.log])
 
 dnl 1. Send an ICMP port unreach reply for port 8738, without any previous request
-AT_CHECK([ovs-ofctl -O OpenFlow13 packet-out br0 2 ct\(table=0\) 'f64c473528c9c6f54ecb72db080045c0003d2e8700004001f355ac100004ac1000030303553f0000000045000021317040004011b138ac100003ac10000411112222000d20966369616f0a'])
+AT_CHECK([ovs-ofctl -O OpenFlow13 packet-out br0 2 resubmit\(,0\) 'f64c473528c9c6f54ecb72db080045c0003d2e8700004001f351ac100004ac1000030303da490000000045000021317040004011b138ac100003ac10000411112222000d20966369616f0a'])
 
 dnl 2. Send and UDP packet to port 5555
-AT_CHECK([ovs-ofctl -O OpenFlow13 packet-out br0 1 ct\(commit,table=0\) 'c6f94ecb72dbe64c473528c9080045000021317040004011b138ac100001ac100002a28e15b3000d20966369616f0a'])
+AT_CHECK([ovs-ofctl -O OpenFlow13 packet-out br0 1 resubmit\(,0\) 'c6f94ecb72dbe64c473528c9080045000021317040004011b138ac100001ac100002a28e15b3000d20966369616f0a'])
 
 dnl 3. Send an ICMP port unreach reply for port 5555, related to the first packet
-AT_CHECK([ovs-ofctl -O OpenFlow13 packet-out br0 2 ct\(table=0\) 'e64c473528c9c6f94ecb72db080045c0003d2e8700004001f355ac100002ac1000010303553f0000000045000021317040004011b138ac100001ac100002a28e15b3000d20966369616f0a'])
+AT_CHECK([ovs-ofctl -O OpenFlow13 packet-out br0 2 resubmit\(,0\) 'e64c473528c9c6f94ecb72db080045c0003d2e8700004001f355ac100002ac1000010303553f0000000045000021317040004011b138ac100001ac100002a28e15b3000d20966369616f0a'])
 
 dnl Check this output. We only see the latter two packets, not the first.
 AT_CHECK([cat ofctl_monitor.log], [0], [dnl
-NXT_PACKET_IN2 (xid=0x0): cookie=0x0 total_len=47 ct_state=new|trk,in_port=1 (via action) data_len=47 (unbuffered)
+NXT_PACKET_IN2 (xid=0x0): table_id=1 cookie=0x0 total_len=75 ct_state=inv|trk,in_port=2 (via action) data_len=75 (unbuffered)
+icmp,vlan_tci=0x0000,dl_src=c6:f5:4e:cb:72:db,dl_dst=f6:4c:47:35:28:c9,nw_src=172.16.0.4,nw_dst=172.16.0.3,nw_tos=192,nw_ecn=0,nw_ttl=64,icmp_type=3,icmp_code=3 icmp_csum:da49
+NXT_PACKET_IN2 (xid=0x0): table_id=1 cookie=0x0 total_len=47 ct_state=new|trk,in_port=1 (via action) data_len=47 (unbuffered)
 udp,vlan_tci=0x0000,dl_src=e6:4c:47:35:28:c9,dl_dst=c6:f9:4e:cb:72:db,nw_src=172.16.0.1,nw_dst=172.16.0.2,nw_tos=0,nw_ecn=0,nw_ttl=64,tp_src=41614,tp_dst=5555 udp_csum:2096
-NXT_PACKET_IN2 (xid=0x0): cookie=0x0 total_len=75 ct_state=rel|rpl|trk,in_port=2 (via action) data_len=75 (unbuffered)
+NXT_PACKET_IN2 (xid=0x0): table_id=1 cookie=0x0 total_len=75 ct_state=rel|rpl|trk,in_port=2 (via action) data_len=75 (unbuffered)
 icmp,vlan_tci=0x0000,dl_src=c6:f9:4e:cb:72:db,dl_dst=e6:4c:47:35:28:c9,nw_src=172.16.0.2,nw_dst=172.16.0.1,nw_tos=192,nw_ecn=0,nw_ttl=64,icmp_type=3,icmp_code=3 icmp_csum:553f
 ])
 
+AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(172.16.0.1)], [0], [dnl
+udp,orig=(src=172.16.0.1,dst=172.16.0.2,sport=<cleared>,dport=<cleared>),reply=(src=172.16.0.2,dst=172.16.0.1,sport=<cleared>,dport=<cleared>)
+])
+
+AT_CHECK([ovs-appctl dpctl/dump-conntrack | FORMAT_CT(172.16.0.3)], [0], [dnl
+])
+
 OVS_TRAFFIC_VSWITCHD_STOP
 AT_CLEANUP
 
-- 
2.10.2